Question

Solve the expression (x-2y)³.
$\left[2Marks\right]$

Answer 1

Given expression: (x-2y)³.

We know that (a-b)³ = a³-3a²b+3ab²– b³

In the expression (x-2y)³, a = x and b = 2y.

Now, substitute the value in the a-b whole cube formula, we get

(x-2y)³ = x³– 3(x)²(2y) + 3(x)(2y)² – (2y)³
$\left[1Mark\right]$

(x-2y)³ = x³ – 6x²y+12xy² – 8y³.

Hence, (x-2y)³ = x³ – 6x²y+6xy² – 8y³.
$\left[1Mark\right]$